package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService iSeckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private RedissonClient redissonClient;
    @Resource
    private StringRedisTemplate stringRedisTemplate;


    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    //写入静态代码块，减少io
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }


    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct   //在当前类初始化完成以后执行以下操作
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }


    private class VoucherOrderHandler implements Runnable {
        private final String queueName = "stream.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    // 0.初始化stream
                    initStream();
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 3.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }

        public void initStream() {
            Boolean exists = stringRedisTemplate.hasKey(queueName);
            if (BooleanUtil.isFalse(exists)) {
                log.info("stream不存在，开始创建stream");
                // 不存在，需要创建
                stringRedisTemplate.opsForStream().createGroup(queueName, ReadOffset.latest(), "g1");
                log.info("stream和group创建完毕");
                return;
            }
            // stream存在，判断group是否存在
            StreamInfo.XInfoGroups groups = stringRedisTemplate.opsForStream().groups(queueName);
            if (groups.isEmpty()) {
                log.info("group不存在，开始创建group");
                // group不存在，创建group
                stringRedisTemplate.opsForStream().createGroup(queueName, ReadOffset.latest(), "g1");
                log.info("group创建完毕");
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有消息，继续下一次循环
                        break;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 3.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getId();
        // 创建锁对象
        // SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 获取锁
        boolean isLock = lock.tryLock();
        // 判断是否获取锁成功
        if (!isLock) {
            // 获取锁失败，返回错误或重试
            log.error("不允许重复下单");
            return;
        }
        try {
            // 获取代理对象（事务）
            createVoucherOrder(voucherOrder);
        } finally {
            // 释放锁
            lock.unlock();
        }
    }

    IVoucherOrderService proxy;

    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId)
        );
        int r = result.intValue();
        // 2.判断结果是否为0
        if (r != 0) {
            // 2.1.不为0 ，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 4.返回订单id
        return Result.ok(orderId);
    }

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 5.一人一单
        Long userId = voucherOrder.getUserId();

        // 5.1.查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        // 5.2.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            log.error("用户已经购买过一次！");
            return;
        }

        // 6.扣减库存
        boolean success = iSeckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) // where id = ? and stock > 0
                .update();
        if (!success) {
            // 扣减失败
            log.error("库存不足！");
            return;
        }

        // 7.创建订单
        save(voucherOrder);
    }
  /*

   private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while (true) {
                //获取阻塞对列中的订单信息
                try {
                    VoucherOrder voucherOrder = orderTasks.take();
                    //创建订单
                    createVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常");
                }
            }
        }
    }*/
/*    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        //执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString()
        );
        int r = result.intValue();
        //判断结果是否为0，不为0，代表没有购买资格，，为0就去购买
        if (r != 0) {
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //结果为0，把下单信息保存到消息队列(阻塞对列)
        //创建订单，返回订单id
        VoucherOrder voucherOrder = new VoucherOrder();
        long orderId = redisIdWorker.nextId("order");
        //订单id
        voucherOrder.setId(orderId);
        //用户id
        voucherOrder.setUserId(userId);
        //代金券id
        voucherOrder.setVoucherId(voucherId);
        //把下单信息保存到消息队列
        orderTasks.add(voucherOrder);

        return Result.ok(orderId);
    }*/


   /* @Override
    public Result seckillVoucher(Long voucherId) {
        //查询优惠券
        SeckillVoucher voucher = iSeckillVoucherService.getById(voucherId);
        //判断秒杀是否开始，是否已经结束
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("活动尚未开始:(");
        }
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("活动已经结束，请保持持续关注:)");
        }
        //判断库存是否充足
        if (voucher.getStock() < 1) {
            return Result.fail("很遗憾，库存不足了>.<");
        }
        return createVoucherOrder(voucherId);


    }

    @Transactional    //添加自定义的redis分布式锁，解决集群模式下安全问题
    public Result createVoucherOrder(Long voucherId) {
        //做一个一人只能下单一单的判断
        //查询订单，判断是否存在，userId,vocherOrderId
        Long userId = UserHolder.getUser().getId();
        //锁对象创建
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = lock.tryLock();

        if (!isLock) {
            //获取锁失败，返回或者重试
            return Result.fail("不允许重复下单");
        }

        try {
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            if (count > 0) {
                //用户已经有优惠券了，不能再抢了
                return Result.fail("该用户已经拥有优惠券了，请把机会让给其他更多需要的人吧！");
            }

            //扣减库存，采用CAS（compare and set)方法，确保多线程情况下，库存的一致性问题，保证不会发生库存超卖的情况
            boolean isStockOrder = iSeckillVoucherService.update()
                    .setSql("stock=stock-1")      //set stock =stock -1
                    .eq("voucher_id", voucherId)  //where id=? and stock =?
                    .gt("stock", 0).update();

            if (!isStockOrder) {
                //扣减失败
                return Result.fail("库存不足");
            }

            //创建订单，返回订单id
            VoucherOrder voucherOrder = new VoucherOrder();
            long orderId = redisIdWorker.nextId("order");
            //订单id
            voucherOrder.setId(orderId);
            //用户id

            voucherOrder.setUserId(userId);
            //代金券id
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);

            return Result.ok(orderId);
        } finally {
            lock.unlock();
        }

    }*/
/*
   @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Transactional    //添加自定义的redis分布式锁，解决集群模式下安全问题
    public Result createVoucherOrder(Long voucherId) {
        //做一个一人只能下单一单的判断
        //查询订单，判断是否存在，userId,vocherOrderId
        Long userId = UserHolder.getUser().getId();
        //锁对象创建
        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        boolean isLock = lock.tryLock(1200);


        if (!isLock) {
            //获取锁失败，返回或者重试
            return Result.fail("不允许重复下单");
        }

        try {
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            if (count > 0) {
                //用户已经有优惠券了，不能再抢了
                return Result.fail("该用户已经拥有优惠券了，请把机会让给其他更多需要的人吧！");
            }

            //扣减库存，采用CAS（compare and set)方法，确保多线程情况下，库存的一致性问题，保证不会发生库存超卖的情况
            boolean isStockOrder = iSeckillVoucherService.update()
                    .setSql("stock=stock-1")      //set stock =stock -1
                    .eq("voucher_id", voucherId)  //where id=? and stock =?
                    .gt("stock", 0).update();

            if (!isStockOrder) {
                //扣减失败
                return Result.fail("库存不足");
            }

            //创建订单，返回订单id
            VoucherOrder voucherOrder = new VoucherOrder();
            long orderId = redisIdWorker.nextId("order");
            //订单id
            voucherOrder.setId(orderId);
            //用户id

            voucherOrder.setUserId(userId);
            //代金券id
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);

            return Result.ok(orderId);
        }   finally {
            lock.unLock();
        }

    }*/

/*
    @Transactional   //集群模式下锁对象锁不住，因为是不同的tomcat不同的jvm，监测的不是同一把锁
    public Result createVoucherOrder(Long voucherId) {
        //做一个一人只能下单一单的判断
        //查询订单，判断是否存在，userId,vocherOrderId
        Long userId = UserHolder.getUser().getId();
        //锁对象的userId
        synchronized (userId.toString().intern()) {
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            if (count > 0) {
                //用户已经有优惠券了，不能再抢了
                return Result.fail("该用户已经拥有优惠券了，请把机会让给其他更多需要的人吧！");
            }

            //扣减库存，采用CAS（compare and set)方法，确保多线程情况下，库存的一致性问题，保证不会发生库存超卖的情况
            boolean isStockOrder = iSeckillVoucherService.update()
                    .setSql("stock=stock-1")      //set stock =stock -1
                    .eq("voucher_id", voucherId)  //where id=? and stock =?
                    .gt("stock", 0).update();

            if (!isStockOrder) {
                //扣减失败
                return Result.fail("库存不足");
            }

            //创建订单，返回订单id
            VoucherOrder voucherOrder = new VoucherOrder();
            long orderId = redisIdWorker.nextId("order");
            //订单id
            voucherOrder.setId(orderId);
            //用户id

            voucherOrder.setUserId(userId);
            //代金券id
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);

            return Result.ok(orderId);
        }
    }
    */


}
